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A delegate is a form of type-safe function pointer used by the Common Language Infrastructure (CLI). Delegates specify a method to call and optionally an object to call the method on. Delegates are used, among other things, to implement callbacks and event listeners. A delegate object encapsulates a reference to a method.
For instance, when the user clicks the close box, the window manager sends the delegate a windowShouldClose: call, and the delegate can delay the closing of the window, if there is unsaved data represented by the window's contents. Delegation can be characterized (and distinguished from forwarding) as late binding of self: [4]
In the delegate pattern, this is instead accomplished by explicitly passing the original object to the delegate, as an argument to a method. [1] " Delegation" is often used loosely to refer to the distinct concept of forwarding , where the sending object simply uses the corresponding member on the receiving object, evaluated in the context of ...
Like the Qt framework's pseudo-C++ signal and slot, C# has semantics specifically surrounding publish-subscribe style events, though C# uses delegates to do so. C# offers Java-like synchronized method calls, via the attribute [MethodImpl(MethodImplOptions.Synchronized)], and has support for mutually-exclusive locks via the keyword lock.
Delegate (CLI), a form of type-safe function pointer used by the Common Language Infrastructure (CLI), specifying both a method to call and optionally an object to call the method on. See also [ edit ]
It should be possible to define a new operation for (some) classes of an object structure without changing the classes. When new operations are needed frequently and the object structure consists of many unrelated classes, it's inflexible to add new subclasses each time a new operation is required because "[..] distributing all these operations across the various node classes leads to a system ...
This reference can then be stored in a delegate-type variable or passed to a method through a delegate parameter for later invocation. C# delegates support covariance and contravariance, and can hold a reference to any signature-compatible static method, instance method, anonymous method or lambda expression.
The adapter [2] design pattern is one of the twenty-three well-known Gang of Four design patterns that describe how to solve recurring design problems to design flexible and reusable object-oriented software, that is, objects that are easier to implement, change, test, and reuse.